In the context of transportation planning and access management for Huron County, ensuring efficient and safe access to the County road network is essential. The following sections provide a comprehensive overview of key design criteria and warrant criteria related to access management, including capacity and level of service, auxiliary turn lanes, traffic control signals, all-way stops, roundabouts, pedestrian crossing treatments, and on-street parking.
6.1 Capacity and Level of Service
The foundation of access management lies in maintaining adequate capacity and acceptable levels of service (LOS) for all movements at access points to the County road system. Access connections must be designed to operate efficiently, particularly during peak hours, and ensure the safety of all road users. Left-turn movements from the arterial road network should operate within a volume-to-capacity (v/c) ratio of less than 0.90 and at an acceptable LOS of D or better. Left-turn movements onto the arterial network should also operate within capacity, ensuring manageable delays and queues.
When a level of service deteriorates or if operational and safety impacts arise, access restrictions may be implemented. These can include directional prohibitions, such as right-in/right-out movements, or other measures like roadway or traffic control improvements, joint access arrangements, and common internal driveways. These measures are aimed at maintaining a safe and efficient flow of traffic, particularly on arterial roads.
If during peak hour conditions, it is observed that the capacity exceeds the acceptable thresholds, and there are risks of adverse operational or safety outcomes, the introduction of mitigation measures becomes necessary. Such interventions could also involve geometric design changes that reduce conflict points and improve the overall flow of traffic.
6.2 Auxiliary Turn Lanes
Auxiliary turn lanes, particularly left- and right-turn lanes, are critical components of access management as they improve traffic flow and reduce conflict points. The need for these lanes is determined based on a Traffic Impact Assessment (TIA) accepted by Huron County, with specific guidelines provided for both left- and right-turn lanes.
6.2.1 Left-Turn Lanes
According to the Ministry of Transportation Ontario (MTO) Design Supplement for the TAC Geometric Design Guide for Canadian Roads, left-turn lane warrants are based on volume thresholds and collision data. A left-turn storage lane may be considered where there are four or more collisions related to left-turn movements per year or six or more in two years. These collisions should be of a type that could be reduced or prevented by installing a left-turn lane. The minimum storage length for such a warrant is 15 meters.
Adequate spacing between access points is also necessary to avoid overlaps of left-turn lanes. All design standards for left-turn lanes must comply with the latest TAC Geometric Design Guide for Canadian Roads, ensuring consistency with best practices in access management.
6.2.2 Right-Turn Lanes
Right-turn lanes, although generally more efficient than left-turn lanes, can still experience conflicts, particularly with pedestrian movements. Exclusive right-turn lanes may be warranted when the volume of right-turning vehicles is between 10 to 20 percent of the through volume, with a minimum of 60 vehicles per hour during the design hour. The decision to provide a right-turn lane should also consider the design speed of the road.
The TAC Geometric Design Guide recommends installing a right-turn lane when the volume of decelerating or accelerating vehicles creates undue hazards, especially when considering pedestrian conflicts and adjacent land use.
6.3 Traffic Control Signals
Traffic signals at private access points are considered primarily in the context of major developments, as determined through a TIA. Traffic signals should only be installed if intersection traffic volumes and other criteria meet the warrant requirements outlined in Ontario Traffic Manual (OTM) Book 12 – Traffic Control Devices. Warrant analysis for signalization includes conducting intersection turning movement counts to determine if the thresholds for signalization are met.
Signalized access points provide a controlled environment for vehicle and pedestrian movements, improving safety and reducing conflict points. However, unnecessary signalization can lead to increased delays and reduced efficiency for arterial roadways, so the justification for signals must be rigorously evaluated.
6.4 All-Way Stops
All-way stop control may be considered on arterial roads in specific situations, as per OTM Book 5 – Regulatory Devices. These situations include:
- Interim measure: When traffic signals are warranted but cannot be immediately implemented.
- Transition periods: To help drivers adapt to changes in intersection control from one direction to another.
- Collision reduction: At locations with a high collision frequency, particularly when less restrictive measures have failed to address the problem. The manual suggests that an all-way stop may be considered if there is an average of four collisions per year that could be prevented by such control, measured over a three-year period.
An all-way stop should not be used for speed control, on roads with a posted speed limit over 60 km/h, or as a means to deter through traffic in residential areas. The decision to implement an all-way stop must also satisfy the vehicular volume and accident criteria outlined in OTM Book 5.
6.4.2 Removal of All-Way Stops
Over time, the conditions that justified an all-way stop may change. A re-evaluation of the need for the traffic control device should be conducted periodically, using recent traffic counts and sightline assessments. If the intersection no longer meets volume warrants and adequate sightlines are present, the intersection should revert to two-way stop control, with free flow for the major road. The change in traffic control should be well-signed to alert motorists.
6.5 Roundabouts
Roundabouts are increasingly being used as an alternative to traditional intersections due to their safety and operational benefits. Roundabouts can reduce the frequency and severity of collisions by minimizing conflict points and lowering speeds at the intersection. In comparison to stop-controlled or signalized intersections, roundabouts can also reduce delays and queues at lower traffic volumes.
From an access management perspective, roundabouts offer a safer and more efficient way to manage turning movements at intersections and driveways, provided access is not directly permitted into the roundabout circulatory roadway. Additionally, roundabouts provide safer U-turn opportunities, eliminating difficult midblock left-turns and reducing the number of full-movement access points along a corridor.
Huron County may consider roundabout installations in certain locations where they offer advantages over more conventional intersection treatments. Appendix C of the guidelines includes a Roundabout Screening Tool, which provides a quick assessment of whether a roundabout is feasible at a given location. This tool is intended to guide the County in deciding whether to proceed with a more detailed Intersection Control Study to further investigate the roundabout's feasibility.
6.6 Pedestrian Crossing Treatments
Pedestrian safety is a key component of access management, particularly in areas with high pedestrian activity. Pedestrian crossing treatments should be considered where a significant number of pedestrians need to cross the roadway and where no controlled crossings are available within a reasonable walking distance. The decision to install pedestrian crossings is based on the criteria outlined in OTM Book 12 – Traffic Signals and OTM Book 15 – Pedestrian Crossing Treatments.
OTM Book 15 provides a decision-making framework for selecting appropriate pedestrian crossing treatments. These treatments may include signalized crossings, pedestrian islands, and other facilities designed to enhance pedestrian safety and accessibility.
6.7 On-Street Parking
While on-street parking can have positive effects in commercial and settlement areas, such as supporting local businesses and enhancing street vibrancy, it also has significant implications for roadway capacity and safety. On-street parking is generally discouraged in areas where it would negatively impact the road’s capacity and operational efficiency, particularly on arterial and collector roads. Developments are encouraged to provide sufficient on-site parking to meet demand.
In certain environments, such as main street retail areas, on-street parking can contribute to a more vibrant pedestrian environment and help slow down traffic. However, the placement and design of on-street parking should be carefully managed to minimize safety risks, particularly near intersections and during peak traffic periods.
Studies have shown that on-street parking can reduce roadway capacity by up to one third. The effect of on-street parking on capacity varies based on factors such as the number of lanes, the distance from intersections, and the time of day. Table 6.1 provides guidelines for assessing the impact of on-street parking on arterial and collector road capacity.
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